Condensation Polymers (Chapter 27.3) Flashcards

1
Q

What are two important condensation polymers?

A

Polyesters and polyamides

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2
Q

What are common starting materials of condensation polymers?

A

Carboxylic acids and their derivatives

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3
Q

What is condensation polymerisation?

A

The joining of monomers with the loss of a small molecule, usually H2O or HCl

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4
Q

What is needed for condensation polymerisation?

A

Two different functional groups

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5
Q

Describe the formation of a polyester

A
  • When making a polyester, monomers are joined together by ester linkages in a long chain to form the polymer
  • Polyesters can be made from one monomer containing both a carboxylic acid and an alcohol group or from two monomers (one with 2 COOH groups and one with 2 OH groups)
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6
Q

What is an example of a polyester made from one monomer?

A
  • Poly(glycolic acid) (PGA)

- Glycolic acid: OHCHCOOH

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7
Q

What is an example of polyester made from two monomers?

A
  • Terylene made from one diol (ethane-1,2-diol) and one dicarboxylic acid (benzene-1,4-carboxylic acid)
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8
Q

Describe the formation of a polyamides

A
  • They are formed when monomers are joined together by amide linkages in a long chain to form the polymer
  • They can be made from one monomer containing both a carboxylic acid/acyl chloride and an NH2 group or from two monomers (one with two COOH/COCl groups and one with two NH2 groups)
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9
Q

What is an example of a polyamide from one monomer

A
  • Amino acids (monomers with NH2 and COOH groups) undergo condensation polymerisation to form polypeptides/proteins
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10
Q

What is an example of a polyamide from two monomers?

A
  • Nylon is formed from one diamine (1,6-diaminohexane) and one dicarboxylic acid (hexanedioic acid) or one diacyl chloride (hexanedioyl chloride)
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11
Q

What is the by-product of condensation polymerisation if an acyl chloride is used?

A

HCl

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12
Q

How can polyesters and polyamides (condensation polymers) be hydrolysed?

A

Using hot aqueous alkali e.g. NaOH or acid e.g. HCl

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13
Q

What are the products of the acidic hydrolysis of polyesters?

A

Dicarboxylic acid and diol

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14
Q

What are the products of the alkali hydrolysis of polyesters?

A

Diol and dicarboxylate salt+Na+

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15
Q

What are the products of the acidic hydrolysis of polyamides?

A

Dicarboxylic acid and diammonium salts (NH3+ on the end)

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16
Q

What are the products of the alkali hydrolysis of polyamides?

A

Diamine and dicarboxylate salt+Na+

17
Q

What are the differences between addition polymerisation (2) and condensation polymerisation (3)?

A

Addition polymerisation:
1) monomer has C=C double bond
2) the backbone of the polymer is a continuous chain of carbon atoms
Condensation polymerisation:
1) two monomers, each with two of the same functional group/one monomer with two different functional groups
2) the polymer contains ester or amide linkages

18
Q

What is Kevlar formed from and why is it strong?

A
  • It is formed from benzene-1,4-dicarboxylic acid and benzene-1,4-diamine
  • It is strong due to the increase intermolecular forces between the aromatic rings as they are planar - ∴ there are stronger hydrogen bonds as the electron density of the two rings can overlap
19
Q

Why are condensation polymers more biodegradable than addition polymers?

A
  • The ester bond in condensation polymers can be hydrolysed by microorganisms in soil and can absorb UV radiation so is photodegradable
  • Addition polymers have a fully saturated alkane backbone which is very unreactive